Mechanical lead pencil



Feb- 4, 1936 w. E. EISENHAUER 2,029,761

MEoHANIcALL-EAD PENCIL Filed sept. 15, 1934 INVENTOB w f FIGB m66 ATTORNEY Patented F eb. 4, 1936 UNITED STATES ATET OFFICE MECHANICAL LEAD PENCIL Wynn E. Eisenhauer, Halifax, Nova Scotia, Canada Application September 13, 1934, Serial No. 743,816 In Canada November 13, 1933 11 Claims.

' to the rate of consumption, the operation of said mechanism being accomplished Without conscious eiTort on the part of the user by the natural writing movements of the thumb and lingers between which the pencil is gripped when in use.

Another feature resides in the provision of simple and easily operated means whereby the lead feeding mechanism may be conveniently adjusted to vary the rate of feed to suit the hardness of the particular lead being used.

A further feature is the provision of a selffeeding pencil of the type described herein which is simple in construction and relatively cheap to manufacture and in which the several parts are assembled so that they are readily accessible for inspection and repair.

The foregoing, together with other features and advantages, are attained by the construction illustrated in the accompanying drawing, in Which- Fig. 1 is a view, in longitudinal section, of a pencil constructed in accordance with this invention.

Fig. 2 is a side elevation of the head section and magazine tube of the pencil.

Fig. 3 is a side view of the barrel section of the pencil.

Fig. 4 is a view, partly in side elevation and partly in longitudinal section, of a follower actuating tube.

Fig. 5 is a perspective view of a follower which works in the magazine tube appearing in Figs. 1 and 2.

Fig. 6 is a perspective View of a brake member which controls the rate at which the lead is fed through the pencil and t Fig. 7 is a side elevation of a brake adjusting sleeve. i

The body of the pencil comprises a barrel section 5 land a head section 6, the latter being rotatably connected with the barrel sectionas herein described. These two sections are provided with registering bores I and 8 which house atube III` which extends from a point adjacent thelowerpoin'ted end 6a of the head section to the upper end of the barrel section.

The tube I4 is internally threaded as at Ida and is keyed to the barrel section 5 as at I5 (Fig. 1). `A second tube 9 is axially arranged within the tube I4. The tube 9 serves as a lead magazine and has its lower end xedly attached in the reduced bore 8a of the tip 6a. Thus it is apparent that the tube Id rotates with the barrel 5 while the tube Il rotates ywith the head 6. The tube Il is provided with a longitudinal slot I3 through which projects a lug I2 of a follower II which is slidably carried within the tube 9. The free end of the lug I2 engages the threads Ita of the tube Ill.

To accomplish my purpose it is necessary, of. course, that the lead be gripped slightly by tube 9 so that tube and lead will rotate together. An alternative arrangement could result from a hollow follower such as is well `known in the art. I prefer the snugly fitting tube as by this arrangement radial play on the part of the lead is eliminated. When the head section 6 and its magazine tube 9 are rotated relative to the barrel section 5 and tube I4 the follower I I is moved toward the point of the pencil through its engagement with the internal thread I Ia of the tube I II. The lower portion of the tube I4 is rotatably tted in the bore 8 of the head section 6 so that head 6 is free to turn relative to the barrel section 5 to which the tube I4 is fixed.

The meeting ends of the bores I and 8 of the barrel and head sections of the pencil are enlarged as indicated at 'Ia and 8b respectively to accommodate a brake adjusting sleeve I6. This sleeve is bored for the passage of the tubes 9 and I4, the lower end of the bore being conically enlarged, as indicated at I8, to receive a frustoconical brake member I 9. 'Ihe latter is also bored for the passage of tube I4 and is split, as indicated at 26, to permit expansion or contraction thereof in response to axial movement of the sleeve I6 relative to the `head section 6. The lower portion of sleeve I6 is in screw threaded engagement with the enlarged portion 8b of the bore 8 while the upper portion of said sleeve is knurled and loosely fttedin the enlarged portion 'Ia of the bore 'I. The rate at which the lead is fed through the point ofthe pencil is .predetermined according to the hardness of the lead by screwing the sleeve into the headsection 6 untilthe contraction of the brake member I9 about the tube IlI- offers the right amount section 6 and the thumb bearing on the barrel section 5, the natural writing movements of the thumb and fingers will set up a torque effect resulting in a slight turning of the head section 6 and tube 9 relative to the barrel section 5 and tube I4. This turning effect is accentuated by the friction of the lead on the writing surface in the following manner. In writing, the downstroke is generally the heaviest stroke and in this stroke the friction of the lead on the paper tends to rotate the lead, together with the tube 9 and tip 6 in the same direction as the fingers turn the tip 6. Thus, on this stroke the turning of the tip 6, tube 9 and lead I 0 is relatively fast. On the up stroke, the friction of the lead on the writing surface opposes the turning of. the tip 6 by the fingers, but because the ngers have a greater leverage and because the up stroke is generally lighter, no reversal of movement on the part of theelead results. At the worst there is but a momentary stoppage of the forward movement. Of course,.in normal writing, the up and down strokes alternate so fast that the forward movement is vcontinuous to all intents and purposes. To permit the pencil to operate properly it is obvious that Ythe adjustment between the brake I9 (which rotates with the head S) and the tube I4 must be carefully regulated. For instance, if

K the adjustmentiis too tight the automatic rotation described above will cease. On the other hand, if the adjustment is too loose the lead will be propelled much too fast. Another item that must be considered is the diameter of the pencil. Thicker or thinner pencils would need different adjustments under the same writing conditions to compensate for the greater or less twisting effectV which would thereby be produced by the fingers on account of the increased leverage afforded by a thicker pencil as opposed to the decreased leverage allowed by a thinner one.

. Thus it is apparent that the invention resides not only in the structure of. the device, but on the particular adjustment of the parts both of which cooperate to produce the desired result. The resulting rotationof magazine tube 9 and follower II with respect to the internally threaded tube I4 causes the follower to move along the magazine to feed the lead through the pointed end of the pencil, the rate of feed being regulated by the braking action of the brake I 9 which is adjusted sov that the rate of feed will correspond substantially to the rate of consumption.

A further feature that obviously follows from Ythe method by which the lead is propelled is that a sharp conical point is automatically provided at all times. Practically all writers hold their pencils at a constant angle to the paper. In using my pencil this constant angle, together with the practically continuous rotation of the lead, results in a sharp point being literally ground on the lead just as if an ordinary pencil were twirled with its point bearing atan angle against a piece of sand paper. Of course, the speed with` which theY point is Vground depends upon the texture of the writing surface. As a result of this, the line produced by the pencil has a. uniform diameter with the eiect that the handwriting is more uniform. At the same time, the pencil always has a fine point which is available for corrections, insertions, interlineations, marginal notes, ,or the like. Y, Y

In connection with writing surfaces it is well to note that when a coarse surface is used the additional friction automatically serves to speedup the rotation and propulsion of. the lead to compensate for the more rapid wear. Conversely, a fine surface provides less friction and the rotation is retarded to avoid propelling the lead too fast. Differences in the wear with respect to leads of different hardness is compensated for by means of the brake I9 as aforesaid.

The bore of the barrel section 5 is enlarged at its upper end to receive an adjustable eraser holder 2| which is bored to accommodate the upper ends of the tubes 9 and I4. The eraser holder carries an eraser 22 and is slidably keyed to the barrel as indicated at 23. The upper end of the holder projects beyond the upper end of the barrel and is externally threaded to receive an internally threaded adjusting cap 24 through which the eraser 22 extends. The cap 24 bears against the upper end of the barrel section 5 so that by turning this cap in the proper direction the eraser holder 2I may be slid outwardly to feed the eraser through the opening at the upper end of the cap.

In order that the pencil may be conveniently secured in the pocket of the user, I provide a clip member 25 normally accommodated in a recess 26 formed in one side of the barrel 5. One end of this clip member is attached to a button shank 2'I which operates in a transverse bore 28 intersecting the bore 1, said shank being provided with an elongated slot 29 through which the tubes 9 and I4 extend with sufficient clearance to permit axial movement of the shank. At the end remote from the clip 25 the shank is provided with a button head 39 working in a recess 3I formed by enlarging one end of the bore 21. A spring 32 confined between the bottom wall of this recess and the button head 30 normally tends to hold the clip 25 within the recess 25. By pressing the button head 39 against the resistance of the spring 32 the clip 25Vis projected out of the recess so that it may be engaged over the outer wall of a coat or other pocket.

Having thus described my invention, what I claim is:-

l. A pencil including two parts, one of said parts being rotatable with respect to the other in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use and to the friction'of the pencil lead on the writing surface, and a lead feeding mechanism operating automatically in response to rotation of said rotatable part.

2. A pencil including two parts, one of said parts being Yrotatable with respect to the other in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use, and to the friction of the pencil lead on the writing surface, a lead magazine, a follower working in said magazine and adapted to feed the lead through the pencil and means, operable by rotation of said rotatable part, for moving the follower in a lead feeding direction.

3. A pencil as claimed in claim 2 and including adjustable means for regulating the rate at which the lead is fed through the pencil.

4. A pencil including two parts, one of said parts being rotatable with respect to the other in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use and to the friction of the pencil lead on the writing` surface, said pencil being equipped with lead feeding means including a lead magazine, a follower movable Yalong the magazine to feed the lead throughY the point of the pencil, means acting in response to rotation of said rotatable part to move the follower in a lead feeding direction and adjustable brake means arranged to resist rotation of said rotatable part to control the rate at which the lead is fed from the magazine.

5. Apencil including two body sections, one of which is rotatable with respect to the other in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use and to thefriction of the pencil lead on the writing surface, `and a lead feeding mechanism housed in said body portion, said feeding mechanism including a member that is moved to feed the lead through the pencil in direct response to the rotation of said body section occasioned by the aforesaid natural writing movement of the thumb and fingers.

6. A pencil comprising a barrel section and a head section, the latter being rotatable with respect to the barrel section in response both to the natural writing movements of the thumb and ngers between which the pencil is gripped when in use, and to the friction of the pencil lead on the writing surface, a lead magazine comprising a tube extending through both sections and fixed to rotate with the head section, a second tube surrounding the magazine tube and fixed to the barrel section, and a lead feeding follower Working in said magazine tube, said follower and said second tube having interengaging parts whereby the follower is moved in a lead feeding direction in response to the aforesaid rotation of the head section by the thumb and fingers.

7. A pencil as claimed in claim 6 including a contractable brake member carried by the head section and surrounding a portion of the tube which is fixed to the barrel section, and means for contracting said brake member into frictional engagement with said tube to control the rate at which the lead is fed from the magazine.

8. A pencil comprising a body portion including a barrel section and a head section, the latter being at the lower end of the barrel and rotatable with respect thereto in response both to the natural writing movements of the thumb and fingers when the pencil is gripped with the first and second fingers bearing on the head section and the thumb bearing on the barrel section and. to the friction of the pencil lead on the writing surface, a lead magazine comprising a tube extending through both of said sections and xed to rotate with the head section, said tube being provided with a lengthwise extending slot, a lead feeding follower working in said tube and having a projection extending outwardly through said slot, and a second tube surrounding said magazine tube and having an internal thread engaging said projection whereby the follower is moved in a lead feeding direction when the head section and the magazine tube are turned with respect to the barrel section and the internally threaded tube.

9. A pencil comprising a barrel section and a head section, the latter being rotatable with respect to the barrel section in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use and to the friction of the pencil lead on the writing surface, a lead magazine comprising a tube extending through both sections and fixed to rotate with the head section, a second tube surrounding the magazine tube and xed to the barrel section, the lower portion of said second tube being rotatably received in said head section, a lead feeding follower working in said magazine tube, said follower and said second tube having interengaging parts whereby the follower is moved in a lead feeding direction in response to rotation of the head section relative to the barrel section, a split frusto-conical brake member surrounding the lower portion of the second tube that is contained in the head section and a brake adjusting sleeve threadedly engaged with the head section and having a bore through which said tubes extend, one end of said bore being conically enlarged to accommodate said brake member, a portion of said adjusting sleeve being loosely housed in the lower end of the barrel section.

10. In a pencil wherein the lead is automatically propelled in response both to the natural writing movements of the thumb and fingers between which the pencil is gripped when in use and to the friction of the pencil lead on the writing surface; adjustable means for regulating the rate at which the lead is propelled.

1l. A self feeding pencil including a body, a lead magazine rotatably mounted within said body and axially thereof, and means actuated by the grip of the user and the friction of the lead on the writing surface whereby said magazine and the lead carried thereby are rotated as the pencil Writes to provide a substantially constant feed of lead from said magazine and to maintain a conical point on said lead.

WYNN E. EISENHAUER: 

